Modern mobile device positioning utilizes a combination of satellite-based and geo-reference based techniques. Existing geo-reference positioning methods generally look up the pre-recorded positions of one or more Radio Frequency (RF) transmitters, such as WiFi access points or cellular base stations, from a centralized database service or from a pre-loaded onboard database. The methods of the prior art generally require real time searching of databases that include a list of all possible Radio Frequency transmitters in a service area. Because of the size of these databases and because the databases may reside on a remote server, the access and search time for determining a position of the mobile device may be extensive. Further, the memory requirements for pre-loading onboard databases may add costs to the device positioning solution.
Some prior art solutions use a mobile device software client to record the presence of 802.11 signals, which are then associated with the current GPS location of the mobile device. The information is then logged into a centralized measurements database server. Information gathered from multiple devices is then analyzed and the estimated position of each 802.11 WiFi access point is calculated, stored in a centralized database and referred to when answering position requests from other clients based on one or more WiFi access points detected.